Processes for joining one piece of ceramic material to either another piece of ceramic material or to a piece of metal have been found to be useful in many fields of technology. Indeed, the fabrication of many complex, multi-functional systems (such as heat exchangers, gas turbines, engines, and other systems that are used at both low and high temperatures) require that ceramics be joined with other ceramics or metals.
In some instances, a metallic brazing technique is used to join one ceramic to another, or to join one ceramic to a metal. However, some metallic brazes can be susceptible to oxidation in oxidizing environments—especially at high temperatures. Accordingly, where a joint that was formed with a metallic braze is used in an oxidizing environment and at high temperatures, oxidation tends to weaken the joint and shorten its operational lifespan.
While some brazing technologies have been improved so that their resultant brazes and joints have an improved resistance to oxidation at high temperatures, such improvements are not necessarily free from shortcomings. For instance, in many cases, the improved oxidation resistance of some brazing techniques may come with a reduction in joint strength and a reduction in the braze's ability to wet a ceramic substrate.
Thus, while techniques for joining one ceramic to another ceramic (or to a metal) exist, challenges with such techniques may also exist, including those previously mentioned. In this regard, there is a need in the art for a way to join specific types of ceramics with the ease of a metal braze (which results in joints that have excellent strength properties in high temperatures) but without the drawbacks that are associated with a joint that has temperature limitations due to oxidation and its associated weakening and property losses. Thus, it would be an improvement in the art to augment or even replace certain conventional brazing techniques with other joining techniques.